Nurdle-boondock is a counting game, the connoisseur's version of the "fizz buzz" children's game. The finesmaster indicates which player will begin, and that player will start by saying either "to my left, one" or "to my right, one". The player seated next to the starting player in the direction specified will then say "two", and play will continue in that direction with the following players saying incrementing numbers.
When "five" or any multiple of five, or any number involving a five is reached (e.g. all the fifties, ten...) the player will say "nurdle", and the next player will be skipped (although counting continues at the next number). When "seven" or any multiple of seven, or any number involving a seven is reached (e.g. 14, 17, 73) then the player will say "boondock" and the direction of play reverses (so the player before the current one plays after him as well). When "nine" or any multiple of nine, or any number involving a nine is reached (19, 91, 63) the player will say "penhaligon", and the numbers on which nurdles and boondocks are activated reverse. Thus 14 is traditionally "nurdle", being after an odd number of penhaligons, and 28 is boondock because it has been preceeded by an even number of penhaligons (9, 18, 19, 27). 25 is traditionally "prefix-cod", where "prefix" is whatever 25 would otherwise have been in the version being played (this originating in an error in nurdle-boondock-category). Nines are sometimes excluded while introducing the game to novices.
When a number meets the requirements of more than one of "nurdle", "boondock" and "penhaligon", all the special words which are relevant are traditionally said in that order: 35 is "nurdle boondock", 27 is "nurdle penhaligon" (because it has been preceeded by an odd number of penhaligons), and 252 is the first "nurdle boondock penhaligon". The penhaligon takes effect after any nurdle or boondock (27 is nurdle-penhaligon because there there were previously an odd number of penhaligons - 9, 18, 19 - rather than boondock-penhaligon as if the penhaligon on 27 were counted first). Given a "nurdle boondock", the direction is reversed before the "next" player is skipped - which means the player who said 34 is skipped.
As a clearer example, consider eight players, A-H, in clockwise
order (as seen from above). The sequence up to forty is:
A: To my left, one
E: nurdle (skips F)
H: boondock (reverses)
F: penhaligon (swaps the numbers of nurdle and boondock)
E: boondock (reverses - there has been an odd number of penhaligons)
H: thirteen A: nurdle (divisible by 7, odd number of penhaligons, skips B)
C: boondock (divisible by 5, odd number of penhaligons)
A: nurdle (has a 7 in it, skips H)
G: penhaligon (divisible by 9)
F: penhaligon (has a 9 in it)
E: boondock (divisible by 5, odd number of penhaligons)
F: nurdle (divisible by 7, odd number of penhaligons, skips G)
C: boondock-cod (traditional on 25)
A: nurdle penhaligon (swaps has a 7 in it, divisible by 9; skips H)
D: nurdle-boondock (divisble by 5 and 7, skips E)
D: boondock (etc.)
One variant is nurdle-boondock-category, in which "penhaligon" is replaced by a word (different each time) from a particular category - the aforemention "cod" derived from an aberrant fish category. There are two variants on this - either the category can be named by the initiator of the round (e.g. "types of cheese, to my left, one") or the category can be implicit, and each Penhaligon should be an entry which is in a possible category; an apparent lack of plausible connection can be challenged, and the player must justify his move.
For example, "to my left, one", "two", "three", "four", "nurdle", "six", "boondock", "eight", "a movie", "boondock", "eleven", "twelve", "thirteen", "nurdle", "boondock", "sixteen", "nurdle", "the sky", "cheese", "challenge". In this case, the player of "cheese" could respond that the category could be "things that can be blue", escaping a fine. (The failed challenger is then fined.) It is up to the finesmaster to request that the category be reset, otherwise it is invalid to repeat any elements in the category that have been named since that category began. It is normal to try to distract the next player by picking a comedy entry in the category.
"Bibble" "bibble" "hic" is another variant that is rarely-played - in this case, every move is "bibble" (including the numbers), but the order of play is in traditional nurdle/boondock/Penhaligon fashion. Note that one might expect "bibble bibble" for numbers such as twenty-seven, and "bibble-cod" for 25. A related variant is to sing the words to the Club Anthem (one at a time) instead of saying "bibble".
Nurdle-boondock-gromp replaces the "penhaligon" with a "gromp", in which the player to say "gromp" indicates (by looking at someone) who is to make the next move. Direction of play is not reversed.
To solve the problem of experienced players having the unfair advantage of having memorised the early numbers (knowing the thirteen-nurdle-boondock-sixteen-nurdle-penhaligon-penhaligon-boondock-nurdle-twenty-two sequence by rote is particularly useful), an option is to draw the numbers on which nurdles, boondocks and penhaligons are to be applied randomly (using the rank of cards as a number from 1-12), rather than sticking to 5, 7 and 9. Another variant is Brussels 2007, in which Nurdle-Boondock is played in French, without Penhaligons, but starting on random numbers.
To assist novices, there is a generator for Nurdle-Boondock-Penhaligon numbers. Of course, this only tells you what the numbers are, not who should be saying them (despite the colour coding).